Effects of the Mental Health Parity and Addiction Equity Act on Specialty Outpatient Behavioral Health Spending and Utilization.

Background: For decades, insurance plans in the United States have applied more restrictive treatment limits and higher cost-sharing burdens for mental health and substance use treatments compared to physical health treatments. The Mental Health Parity and Addiction Equity Act (MHPAEA) required health plans that offer mental health and substance use benefits to offer them at parity with physical health benefits starting in January 2010.

Aims of the study: To determine the effect of MHPAEA on out-of-pocket spending and utilization of outpatient specialty behavioral health services.

Methods: The proportion of individuals with at least one outpatient specialty behavioral health visit, the average number of visits among those with any behavioral health visit, and the proportion of behavioral health spending paid out-of-pocket were obtained from the nationally-representative Medical Expenditure Panel Survey (MEPS) for the years 2006 to 2013. Difference-in-differences models were estimated comparing individuals with employer-sponsored insurance to those with Medicaid, Medicare, or who were uninsured.

Results: Out-of-pocket share of spending was lowest among Medicaid (2.0%) and highest among the uninsured (22%), followed by the employer group (13%). Individuals in Medicaid had the highest proportion of any behavioral health visit (11%) and the uninsured had the lowest (2.4%). Among those with any behavioral health visits, the average number of visits was similar across groups. Our primary and sensitivity analyses suggest MHPAEA did not lead to changes in utilization or spending on specialty outpatient behavioral visits for individuals with employer-sponsored insurance compared to other groups.

Discussion: Potential reasons for MHPAEA's apparent lack of effect are that health plans were already at parity before the law's passage, that many health plans continue to be out of compliance with the law, that concurrent changes in plans' cost-sharing blunted the law's effects, and that other barriers to behavioral health service use continue to limit utilization. While our study cannot provide direct evidence of these mechanisms, we review existing evidence in support of each of them. Our study had several limitations. We cannot test definitively whether the difference-in-differences assumption was violated or fully control for time-varying differences between groups. We attempt to address this by using multiple control groups and presenting evidence of parallel trends before MHPAEA implementation. Second, because our data do not have state identifiers, we cannot control for which states had existing mental health parity laws. Third, a nationally representative analysis may mask substantial heterogeneity for affected subgroups.

Implications for health policies: We find no evidence MHPAEA substantially affected behavioral health utilization or out-of-pocket spending. Federal parity legislation alone is likely insufficient to address barriers to behavioral health affordability and access.